In the UMTS (Universal Mobile Telecommunication system) network, the specifications of long term evolution (LTE) have been drafted for the purpose of further increasing high speed data rates, providing lower delays and so on (see non-patent literature 1). In LTE, as multiple-access schemes, a scheme that is based on OFDMA (Orthogonal Frequency Division Multiple Access) is used in downlink channels (downlink), and a scheme that is based on SC-FDMA (Single Carrier Frequency Division Multiple Access) is used in uplink channels (uplink).
In LTE systems, techniques for achieving further improvement of cell throughput are under study. For example, spatial multiplexing (SDM: Spatial Division Multiplexing) based on MIMO (Multiple Input Multiple Output), inter-base station coordinated (CoMP: Coordinated Multi-Point) transmission/reception and so on are under study.